[amsat-bb] Re: Geostationary Satellite
howied231 at hotmail.com
Tue Oct 11 07:01:20 PDT 2011
I agree with much of what Dan, N8GFV, says. Our best hope of a high altitude satellite is probably a hosted payload on a GEO sat. To make that viable we need to consider the entire mission. GEO satellite operators are a for-profit business and every aspect of a commercial satellite has a dollar value. The major items are spectrum, power and fuel. Since hams bring their own spectrum, that is a no cost item for us. If we need to use satellite power then we would need to pay the market rate for the percentage of the total satellite resource used for the design lifetime of the satellite, typically 15 years. If the payload can be disabled by the operator we may be able to negotiate a pay as you go plan so that we don't have to pre-pay 15 years worth of power. Developing very power efficient transponder systems will reduce our costs. Trading bandwidth for power by using digital encoding, strong FEC, regenerative transponders with DSP signal enhancement will all aid in the reduction of the power required to close a link.
The other big cost factor is fuel. As previously stated here, station keeping is a critical element in GEO satellites and with the advances of component technology, a satellites lifetime in orbit is determined primarily by the amount of station keeping fuel it can carry. The more fuel, the longer the satellite life, the more time the operator can use to recover their investment and make money. Every ounce added to the satellite affects the cost of the launch and possibly the amount of fuel that can be carried on board. Whether this is the case or not, the added satellite weight WILL add to the launch cost that we would have to pay.
The good news is that the AMSAT community and the satellite operators have common interests in making satellites less expensive and more efficient. By building on the technology pioneered in ARISSAT-1 we MAY be able to get some cooperation from a commercial operator to deploy a technology demonstration package as a hosted payload. This might be more probable than one thinks. Satellite operators are EXTREMELY conservative and don't deploy new technology until it is thoroughly proven. The commercial satellite market is running out of real estate. Many of the big operators are at over 80% capacity. Since they are for-profit organizations, they are running out of product quickly and will not be able to grow their business. All the major operators are investing large amounts of money to promote a hosted payload business where government and scientific users can bring their own bandwidth to a transponder or payload on the operators platform. A low cost, high performance, innovative payload COULD be a great advertising tool for a commercial operator. The operator would get the payload for zero cost and could also get part of the launch cost subsidized by AMSAT in return for a real world, open source demonstration tool.
If we build this payload along the lines of Tom Clark's C-C rider concept with a 5 GHz up/ 3 GHz. down transponder we can probably even use the satellites low gain telemetry antenna, further reducing payload costs.
Sorry for the lengthy post but I have been thinking about this for a while and this seemed like a good opportunity to finally put it in writing.
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